Add satip detection script

roles/yavdr-common/files/satip.facts.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+# This script sends a multicast message and awaits responses by Sat>IP servers.
+# returns the boolean variable 'satip_detected' as json
+import json
+import socket
+import sys
+import time
+
+SSDP_ADDR = "239.255.255.250"
+SSDP_PORT = 1900
+# SSDP_MX = max delay for server response
+# a value of 2s is recommended by the SAT>IP specification 1.2.2
+SSDP_MX = 2
+SSDP_ST = "urn:ses-com:device:SatIPServer:1"
+
+ssdpRequest = "\r\n".join((
+    "M-SEARCH * HTTP/1.1",
+    "HOST: %s:%d" % (SSDP_ADDR, SSDP_PORT),
+    "MAN: \"ssdp:discover\"",
+    "MX: %d" % (SSDP_MX),
+    "ST: %s" % (SSDP_ST),
+    "\r\n"))
+
+sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+# according to Sat>IP Specification 1.2.2, p. 20
+# a client should send three requests within 100 ms with a ttl of 2
+sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 2)
+sock.settimeout(SSDP_MX + 0.5)
+for _ in range(3):
+    sock.sendto(ssdpRequest.encode('ascii'), (SSDP_ADDR, SSDP_PORT))
+    time.sleep(0.03)
+try:
+    response = sock.recv(1000).decode()
+    if response and "SERVER:" in response:
+        got_response = True
+    else:
+        raise ValueError('No satip server detected')
+except (socket.timeout, ValueError):
+    got_response = False
+finally:
+    print(json.dumps(
+        {'satip_detected': got_response}
+    ))